1. Field of the Invention
The present invention relates generally to turning lathe for interior cutting.
2. Background of the Invention
Commercial turning lathes usually machine hollow work pieces, in particular long hollow cylindrical work pieces, using boring rods. Differently constructed boring rods are available on the market. They are all gripped at one end leaving the machining of the work piece exposed. The maximum possible boring length for such boring rods is approximately 15 times the diameter of the boring rod. An unfavorable aspect ratio between length and diameter in the work piece results in the inability to perform interior turning tasks of longer lengths.
Furthermore, the tolerances achieved during interior turning of tubes by boring rods that have been gripped at one end and that are exposed are not acceptable. The desired surface roughness can no longer be achieved. Tube manufacturing tolerances, furthermore, cause tool vibrations when different depths of cuts are used, which then lead to an inadequate surface.
Therefore, the so-called deep-hole boring methods in which the boring head is guided are used for interior turning tasks of longer lengths. However, only cylindrical borings are possible in this connection allowing for a high quality surface finish and dimensional accuracy.
It is the object of the present invention to provide a turning lathe for interior cutting of hollow work pieces with which interior turning tasks of longer lengths of the work piece with low tolerances become possible.
This object is achieved by means of a turning lathe according to claim 1.
Preferred embodiments are detailed in the dependant claims.
In accordance with the invention the boring rod is gripped at both ends and held in place and the tool holder device is fitted onto the boring rod in such a way that it is movable. The tool holder device can then, in a controlled manner, move along the boring rod and perform the desired interior turning task.
Basically, it is possible to perform the interior turning task on a hollow work piece simply by making only the tool holder device movable leaving all other components, including the work piece, fixed. Preferably, the tool holder device is movable at least axially along the boring rod and is also operable radially in relation to the axis of the boring rod. However, the work piece can be held in the mechanism for holding a work piece in a manner that allows it to be rotated.
Another advantage of the mechanism for holding a work piece is the presence of detachable chucking systems with chucking heads.
It is preferable if an annular plate functions as the chucking head on every chucking system whereby the work piece is clamped in between the annular plates. It is particularly advantageous if the annular plates are truncated cone housings. This would allow for the machining of thin-walled work pieces. The truncated cone housing shaped annular plates hold the tubular work piece in place in an annular rotating manner and therefore in a perfectly circular manner.
The chucking systems or as the case may be the chucking heads and in particular the annular plates facilitate the rotational operation of the work piece.
At least one of the chucking heads of the work piece should be movable relative to the others so it can be adjusted to fit different lengths of tube.
It is furthermore advantageous to hold the boring rod in place on a boring rod sliding plate in such a manner that it is operable in longitudinal direction along its axis.
The boring rod can also be adjusted to move perpendicular to its axis so that for example slim truncated cone shaped bore holes can be made in tubular work pieces. By simultaneously controlling the boring rod sliding plates and the tool holder device as well as by taking advantage of the different possible settings, helix-like grooves, swellings, convex and other complex shapes can be achieved. Basically, the tool holder device is able to hold for example a lathe tool or geometrically undefined tools so that the turning lathe according to the invention also can be used as a grinder. In addition, a rotating tool can be attached to the tool holder device.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and advantages of the invention will be realized and attained by the structure and steps particularly pointed out in the written description, the claims and the drawings.